Wire wrap tool



Jan 318,, 1966 ROBEY, JR ETAL 3,229,729

WIRE WRAP TOOL Filed Oct. 1, 1963 2 Sheets-Sheet 2 TO MEMORY PLAN E CONNECTlON FIG. 4A

MEMORY PLANE CONNECTION MEMORY PLANE CONNECTION INVENTORS EDMUND L. ROBE Y, JR. and

THOMAS C. STOV/AK uwsmw ATTORNEY.

United States Patent 3,229,729 WIRE WRAP TOOL Edmund L. Robey, 31"., Montoursville, and Thomas C.

Stoviak, Williamsport, Pa., assignors to Sylvania Electric Products Inc, a corporation of Delaware Filed Oct. 1, 1963, Ser. No. 313,050 6 Claims. (Cl. 140-123) This invention relates to a tool for wrapping wire about a terminal lug, and more particularly to a tool for wrapping extremely fine wire about the terminal lugs of a memory plane.

The wire wrap tool of the present invention is useful in a variety of wire wrapping operations, but is particularly suitable for the wire wrapping operations associated with assembly of the improved frame and connection structure for magnetic core memory planes described in co-pending United States application, Serial No. 312,975 filed October 1, 1963, assigned to the assignee of the present invention. As explained therein, such memory planes, which are useful for the storage of data in digital computers, comprise an array of tiny ferrite cores arranged in rows and columns and threaded with extremely fine wire conductors. A typical memory plane might have sixty-four rows and sixty-four columns with the cores having 0.050" or smaller centers strung on copper wire as small as 0.006" in diameter. The row and column wires which support the core array (referred to in the co-pending application as address wires) are tightly strung across a four-sided frame. The magnetic core memory plane frames are assembled from standard strip stock of a suitable dielectric material having a standard arrangement of slots and grooves or pierced holes. Terminal lugs are mounted into the slots and grooves or holes along the outer perimeter of the frame by a snap-in action to provide connection terminals for the address wires of the memory plane.

A preferred terminal lug design described in the abovementioned co-pending application is shown in its mounted configuration in FIGS. 1A, 1B and 1C, which are respectively a front view, a cross-section view taken in the direction of arrows 1B-1B in FIG. 1A, and a cross-section view illustrating the connection of an address wire to a terminal lug. Lug 10 may be a stamping of a thin sheet of suitable material, such as full hard beryllium copper, treated to provide good solderability, for example, by tin plating. It is mounted on the frame strip 14 by hand tool or automatic insertion means by pressing it into an edge slot 12 from above, tilting the lug so that prong 10a clears the frame, and rotating it with a snapin action to secure prong 100 into hole 16. This results in the lug being firmly seated, prong 10a having a chamfer to provide a swaging or gripping action when seated in the hole, the point on hooked portion 10b digging into the frame to provide a secure grip, and the sides of the slot 12 preventing any swaying action. As shown, adjacent lugs are alternately mounted on opposite sides of the frame 14.

Referring now to FIG. 1C, an address wire 18 from the magnetic core matrix, having been threaded through a corresponding row or column of cores by techniques well known to the art, is wrapped around portion 10c of the lug terminal post. A shoulder 11 is provided at the lower end of the portion 100 of the lug to hold the wire at a distance from the frame. After completion of the mechanical wire wrapping operation, the wire is mechanically and electrically secured to the lugs by soldering. Preferably an automatic dip soldering process is employed by which solder is simultaneously applied to all wiring connections along one side of the frame. Post 100 is the portion of the lug dipped in solder; the step 10d helps to prevent unwanted solder bridging between lugs.

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As described in the aforementioned co-pending application, a memory system usually comprises a compact stack of several magnetic core memory planes. For example, a memory system in accordance with the teachings of the co-pending application may have eight planes stacked to the inch. Further, alternate sets of terminal post extensions of adjacent planes are juxtaposed, so as to provide an external series connection between frames after soldering. These factors along with the extremely close spacing of the terminal lugs pose a number of stringent wiring requirements. For example, the wire must be pulled tight, and the first wrap made at the proper position on the terminal post. Each turn of wire must be tightly wrapped against the preceding turn on the terminal post to preclude overlaps, to assure a secure, neat connection to enable a good solder junction, especially between juxtaposed terminal posts, and to avoid unwanted solder bridging between the closely spaced lugs. It is also desirable that the wire be severed, after a fixed number of turns have been wrapped, at a corner of the lug, so as not to leave loose ends of wire which might cause unwanted solder bridging or shorting to adjacent lugs or wires. In addition, for economical production of such memory planes, the above prescribed wire wrapping operation must be performed with a minimum expenditure of time and cost. Available wire wrapping methods have been found unsatisfactory for handling the extremely fine wire (as small as 0.006" in diameter) used in the abovedescribed memory plane.

With an appreciation of the problems raised by the aforementioned wiring requirements, applicants have as a general object of this invention to provide an improved wire wrap tool for wrapping extremely fine wire about terminal lugs. A more specific object is to provide an efficient tool for wrapping extremely fine Wire about closely spaced terminal lugs to thereby provide a connection which, upon soldering, will provide a mechanically and electrically secure junction and preclude unwanted solder bridging.

Another object of the invention is to provide a relatively simple wire wrap tool which determines the position of the first wrap, wraps without overlay of adjacent turns, sets the number of turns as desired, and is adjustable to sever the wire at a desired location.

Briefly, the wire wrap tool according to the invention comprises a tubular shaped body having a lug mounting head at one end, a slot in the head through which the wire is threaded, and a spring loaded rod within the body portion from which a pin extends through a slot in the wall of the body. The wire to be wrapped is threaded through the slot and secured to the extending pin, and as the tool is rotated, the pin moves down within the slot, and the rod to which the pin is mounted bottoms after a preadjusted number of turns are applied. Further rotation causes a tension which break the wire at a corner of the lug. The shape of the head and the spring loading of the pin cooperate to force the wrapped turns to advance on the terminal post and to prevent overlap.

Other objects, features and advantages of the invention will become apparent, and a better understanding of its construction and operation will be had, from the following detailed description taken in conjuncttion with the accompanying drawings, in which:

FIGS. 1A, 1B and 1C to which previous reference has been made, show front and cross-sectional fragmentary views of a terminal lug design with which the tool according to the invention has particular utility;

FIG. 2 is a front elevation view of the wire wrap tool according to the invention;

FIG. 3 is a cross-section view taken along line 3-3 of FIG. 2; and

FIGS. 4A, 4B and 4C are fragmentary side views, greatly enlarged, of the portion of the tool which engages the terminal lug, showing progressive steps of the wire wrapping operation.

Referring to FIGS. 2 and 3, which are enlarged about two times, the present Wire wrap tool comprises a tubular body portion or enclosure joined to a generally tubular head portion 22 :by a cylindrical bushing 24 threaded at its ends into the body and head portions. The free end of the head portion 22 is formed with a generally cylindrical projection 23, of small dimensions, having a wire receiving slot 26 formed therein. As shown in FIG. 3, the bottom of the slot is parallel to and oiT-set from the longitudinal axis of the body portion. The projection 23 ha a depression or concavity 28 formed in its extremity shaped to receive the free end of the lug to be wrapped whereby the lug provides a pivot upon which the tool may be rotated about a longitudinal axis substantially coincident with the bottom of slot 26. The end of the projection 23 is tapered at 27 (best seen in FIGS. 4A4C) to prevent overlap of adjacent turns of the wrapped wire, as will be more clearly seen hereinafter.

As shown, the bores of the body and head portions are of somewhat larger diameter than the bore of bushing 24. A cylindrical stop member 32 is disposed within the bore of the head portion 22, to slidably engage the inner wall thereof, and is adapted to bottom against the lower end face 33 of the bore. A colinear cylindrical rod is secured to the other end of the stop member 32 and slidably extends through the bore in bushing 24 into the bore of the body portion 20. The stop member is adapted to move within the bore of head portion between the bottom and the point at which it meets the lower shoulder 24a of bushing 24. A pin 34, secured to and extending radially from stop member 32, projects through a longitudinal slot 36 in the wall of the head portion, the slot being sufiiciently long as to not interfere with the range of travel of the stop member. The outer end of the pin is formed with a slot for receiving the wire 18 to facilitate temporary attachment of the wire to the pin.

Within the body portion 20 of the tool, a spring 38 surrounds the upper portion of rod 30, being held in compression between the upper shoulder 24b of the bushing and a nut 40 threaded onto the upper end of the rod. The degree of compression may be adjusted by changing the position of nut 40, the latter being maintained in adjusted position by a lock nut 42. Unless it is constrained, it is apparent the rod and spring assembly thus far described would cause the stop member 32 to assume a position against the lower shoulder 24a of the bushing. The number of turns to be wrapped on a lug of a given circumference being determined by the travel of the pin 34 from an initial position to the position at which the stop member 32 bottoms against face 33, an adjusting screw 44, threaded into the upper end of rod 30 is provided to adjust the initial position of the pin 34. To prepare the tool for a particular wire wrap operation, the compression of spring 38 is first set by adjustment of the position of nut 40 on rod 30, and stop member 32 (and the pin 34 carried thereon) moved to the proper longitudinal position in the bore by the appropriate amount of insertion of adjusting screw 44. A suitable locking screw 46 may be provided to secure the entire adjustment. More turns will be wrapped on the lug before severing of the wire when the initial position is near the upper end of slot 36 than when the initial position is nearer the lower end thereof.

Referring to FIGS. 4A, 4B, and 4C, which show the head portion of the tool, greatly enlarged, the manner in which the tool wraps the wire will now be described. The end of the lug on which the wire is to be wrapped is inserted into the concavity 28 at the end of the head, and the tool positioned with its longitudinal axis parallel with the length dimension of the lug. The wire 18 to be wrapped, one end of which is secured to the opposite side strip of the memory plane frame, is laid in the wirereceiving slot 26 in the projection 23 and fastened to pin 34, which is in a selected initial position as determined by the above-described adjustment procedure. Upon turning the tool one revolution clockwise (as viewed from the right end in FIG. 4A) about an axis coincident with the long axis of lug 10c, and with the lug as a pivot, the wire is wrapped once around the lug close to the shoulder 11, as shown in FIG. 4B. It will also be noted from this figure that wrapping of one turn has moved the pin 34 the distance Y from its initial position against the compression of spring 38, and the end of stop member 30 the distance Y closer to the bottom face 33 of the bore in head portion 22. After a second revolution of the tool, depicted in FIG. 4C, two turns are laid on the lug and pin 34 has moved the distance X'from its position in FIG. 4B. The second turn does not overlap the first because of the inclined face 27 at the end of the projection 23, to which the wire tends to conform to cause the second turn to start closer to the head than the previous turn, and the spring loading on pin 34 which urges the wire away from the shoulder 11 of the lug. Further rotation of the tool causes further turns of wire to be wrapped until stop member 32 bottoms against the face 33, whereupon further rotation causes the wire to break. Significantly, the wire breaks at the highest stress point, which is always at the corner of the rectangularly-shaped lug contacted by the wire closest to the end of groove 26 at the time stop member 32 bottoms. This gives the desirable result of preventing loose ends at the end of the wrap which could cause undesirable solder points or bridging of solder. Although the wrapping of only two turns has been illustrated, a greater number, determine-d by the above-described adjustment of the initial position of pin 34, is usually wrapped, and the two adjustments provide sufiiciently close control that the wire can be made to always break at the same corner of the lug after the selected number of turns have been laid down.

Although a hand tool has been described, it is readily adaptable to motorization to cause rotation about the axis 48 in FIG. 3.

The present invention, therefore, provides a simple wire wrap tool that will determine the first wrap position, wrap without overlay turns, set the number of turns desired and break the wire at the corner of the lug, so as to leave no loose ends of wire. A hand tool constructed and operated as described has successfully wrapped copper-wire as small as 0.006" diameter.

Although there has been described what are now considered to be preferred embodiments of the invention, modifications falling within the scope and spirit of the invention will occur to those skilled in the art. For example, the compression spring may be replaced with an air spring, and the general shape and adjustment features may deviate from the specific structures shown and described. It is the intention, therefore, that the invention is not to be limited by what has been specifically illustrated and described, except as such limitations appear in the appended claims.

What is claimed is:

1. For wrapping wire about a terminal lug, a wire wrap tool comprising, an elongated enclosure having a bore of predetermined length formed therein, a stop member shorter than said bore slidably positioned within said bore for longitudinal movement therein over a predetermined range, a cylindrical longitudinal projection at one end of said enclosure having a coextensive longitudinal wire-receiving slot in its outer surface and a depression at its free end for receiving one end of a terminal lug, means for securing an end of the wire to be wrapped to said stop member, and spring means in said enclosure normally urging said stop member in a direction away from said projection.

2. A tool for wrapping wire about a terminal lug comprising, in combination, an elongated enclosure having a longitudinal cylindrical cavity therein, a head extending from one end of said enclosure having a wire receiving slot longitudinally disposed with respect to said enclosure and a concavity at its outer end for engaging one end of said lug, a rod slidably mounted within said cavity, the wall of said cavity being formed with an elongated slot longitudinally aligned with said wire-receiving slot, a pin extending radially from said rod through said elongated slot for securing to said rod an end of the wire to be wrapped, spring means in said enclosure normally urging said rod in a direction away from said head, and means for adjusting the initial longitudinal position of said rod in said bore to determine the number of turns of wire to be wrapped.

3. A tool in accordance with claim 2 wherein said enclosure is tubular, and said last-mentioned means comprises an adjusting screw axially aligned with and engaging said rod at the end opposite the end from which said pin extends.

4. A wire Wrap tool comprising: an elongated cylindrical enclosure having a longitudinal bore therein, a head portion at one end of said enclosure formed With a longitudinal wire threading slot on its outer surface and including a projection aligned with said slot, said projection having a cavity of circular cross-section in its free end for receiving a terminal lug and having in its outer surface a continuation of the slot in said head portion, a cylindrical rod shorter than said bore slidably mounted within said bore, said enclosure having an elongated opening therein aligned with said wire-receiving slot, a pin extending radially from said rod through said elongated opening, a spring normally urging said slidable rod in a direction away from said head portion for preventing overlap of successive wire wraps, and adjusting means for presetting the position of said rod with said bore to limit its motion during a wire wrapping operation.

5. A tool for wrapping wire about a terminal lug comprising, an elongated cylindrical body portion having a bore of predetermined length formed therein near one end thereof, a head portion at said one end of said enclosure including a cylindrical longitudinal projection of substantially smaller cross-sectional dimensions than said body portion and with its longitudinal axis parallel to and laterally offset from the longitudinal axis of said body portion, said head and projection having a longitudinal wire-receiving slot in a surface thereof coextensive with said head portion and projection and a depression in the free end of said projection intersecting said slot for receiving the end of a terminal lug, a cylindrical stop member shorter than said bore slidably positioned within said bore for longitudinal movement therein over a predetermined range, said body portion having a longitudinal slot in the wall of said bore longitudinally aligned with said wire-receiving slot and substantially coextensive with said bore, a pin extending radially from said stop member through said elongated slot to which one end of the wire to be wrapped is adapted to be releasably secured, spring means in said body portion arranged to normally urge said stop member in a direction away from said one end of said body portion, and means within said body portion for adjusting the initial longitudinal position of said stop member to determine the number of turns of wire to be wrapped.

6. A tool for wrapping wire about a terminal lug comprising, an elongated cylindrical body portion having a bore of predetermined length formed therein near one end thereof, a head portion at said one end of said enclosure including a cylindrical longitudinal projection of substantially smaller cross-sectional dimensions than said body portion and with its longitudinal axis parallel to and laterally offset from the longitudinal axis of said body portion, said head and projection having a longitudinal wire-receiving slot in a surface thereof coextensive with said head portion and projection, the free end of said projection being inclined toward said wire-receiving slot and having a substantially circular depression formed therein and intersecting said wire-receiving slot for receiving the end of a terminal lug, a cylindrical stop member shorter than said bore slidably positioned within said bore for longitudinal movement therein over a predetermined range, said body portion having a longitudinal slot in the wall of said bore longitudinally aligned with said wire-receiving slot and substantially coextensive with :said bore, a pin extending radially from said stop member through said elongated slot to which one end of the wire to be wrapped is adapted to be releasably secured, spring means in said body portion arranged to normally urge said stop member in a direction away from said one end of said body portion, and means within said body portion for adjusting the initial longitudinal position of said stop member to determine the number of turns of wire to be wrapped.

CHARLES W. LANHAM, Primary Examiner. 

1. FOR WRAPPING WIRE ABOUT A TERMINAL LUG, A WIRE WRAP TOOL COMPRISING, AN ELONGATED ENCLOSURE HAVING A BORE OF PREDETERMINED LENGTH FORMED THEREIN, A STOP MEMBER SHORTER THAN SAID BORE SLIDABLY POSITIONED WITHIN SAID BORE FOR LONGITUDINAL MOVEMENT THERIN OVER A PREDETERMINED RANGE, A CYLINDRICAL LONGITUDINAL PROJECTION AT ONE END OF SAID ENCLOSURE HAVING A COEXTENSIVE LONGITUDI- 